This invention relates to a jet solder feeding device for feeding molten solder to a substrate by ejecting the molten solder from ejecting ports and to a method for soldering the same.
Jet solder feeding devices are already known in which soldering is carried out for a substrate mounted with electronic parts by feeding molten solder ejected through jet nozzles to the substrate while letting the substrate be conveyed in a prescribed direction.
Jet solder feeding devices of this type include the one which comprises: a first jet nozzle 1 for feeding molten solder J satisfactorily to a substrate P mounted with electronic parts in the whole area of the surface to be soldered and a second jet nozzle 2 for removing excess molten solder J having been fed to the substrate P, as shown in FIGS. 6 and 7. The first jet nozzle 1 and the second jet nozzle 2 are connected to a duct 3 for the first nozzle and a duct 4 for the second nozzle, respectively, both of which are soaked in molten solder J accumulated in a solder melting bath 5. This jet solder feeding device is designed to eject molten solder J from the first jet nozzle 1 and the second jet nozzle 2 toward a substrate-conveying path 10 by rotationally driving impellers 6 and 7 arranged to face each of the openings at one end of the duct 3 and at one end of the duct 4, respectively.
On the upper end portion of the first jet nozzle 1, a corrugated plate 9 with multiple open ejecting ports 8 is mounted. The ejecting ports 8 are provided, for example, in three rows relative to the direction A in which the substrate P is conveyed, and all the ejecting ports 8 are formed at a prescribed pitch M relative to the direction B perpendicular to the direction A in which the substrate P is conveyed in such a manner that more than one ejecting ports 8 are in each row, as shown in FIGS. 8a, 8b. As for the direction B perpendicular to the substrate-conveying direction A, these ejecting ports 8 are staggered in a top view in such a manner that each ejecting port 8 in the row next to the first or second row is located right at a midpoint of the adjacent ejecting ports in the above first or second row which are lined up laterally along the direction B perpendicular to the substrate-conveying direction A.
In this jet solder feeding device, the substrate P is designed to improve wettability of solder in such a manner as to apply flux thereto before soldering.
In the above described conventional jet solder feeding device, however, molten solder J ejected from 4 adjacent ejecting ports 8, in a top view, flows right into the midpoint of the above 4 adjacent ejecting ports 8 while keeping a balanced relationship among the force and direction Fs of its flow, as shown in FIG. 9. Accordingly, when the substrate P is conveyed to a position facing each ejecting port 8 of the first jet nozzle 1 and comes in contact with the molten solder J, gas of vaporized flux or air Q or the like may accumulate in the midpoint of the 4 adjacent ejecting points 8 under the bottom surface of the substrate P. This causes poor wetting since there arise portions where the molten solder J does not come in contact with the substrate P.
The present invention has been made to solve the above problem. Accordingly, the object of the present invention is to provide a jet solder feeding device and a method for soldering which enable the prevention of poor wetting due to the accumulation of gas, air or the like under the bottom surface of the substrate caused when the substrate is conveyed to a position where it is fed with molten solder.
In order to solve the above problem, the present invention is a jet solder feeding device for feeding molting solder to a substrate conveyed in a prescribed conveying direction by ejecting the molten solder from multiple ejecting ports toward a the substrate, wherein, in at least one part of the area including the above multiple ejecting ports, the ejecting ports are provided in more than one rows relative to the substrate-conveying direction, including an upstream row and a downstream row and arranged at a second prescribed pitch in lines substantially along multiple inclined lines which are inclined to the substrate-conveying direction and, being arranged at a first prescribed pitch in the direction perpendicular to the substrate-conveying direction, the above first prescribed pitch being set to be larger than the above second prescribed pitch.
The jet solder feeding device having this configuration enables the prevention of poor wetting due to the accumulation of gas, air or the like under the bottom surface of the substrate caused when the substrate is conveyed to a position where it is fed with molten solder.
The invention in one embodiment is a jet solder feeding device for feeding molten solder to a substrate conveyed in a prescribed conveying direction by ejecting the molten solder from multiple ejecting ports toward the substrate, wherein, in at least one part of the area including the multiple ejecting ports, the ejecting ports are provided in more than one rows relative to the substrate-conveying direction, including an upstream row and a downstream row and arranged at a second prescribed pitch in lines substantially along multiple inclined lines which are inclined to the substrate-conveying direction, and being arranged at a first prescribed pitch in the direction perpendicular to the substrate-conveying direction, the above first prescribed pitch being set to be larger than the above second prescribed pitch.
According to this configuration, since the first prescribed pitch is larger than the second prescribed pitch, the balance of the flowing force of molten solder from each ejecting port is lost between the midpoint of adjacent ejecting ports arranged at the first prescribed pitch and the midpoint of adjacent ejecting ports arranged at the second prescribed pitch. As a result, molten solder flows from the point where its flowing force is larger to the point where its flowing force is smaller. Accordingly, the flow of molten solder passing through midway between adjacent groups of ejecting ports is created positively; therefore when the substrate is conveyed to the position where it is fed with molten solder, even if gas of vaporized flux is generated or air is admixed, the gas generated or the air admixed under the bottom surface of the substrate is satisfactorily discharged along the above described flow to the outside. This means no occurrence of poor wetting.
The invention in another embodiment is a jet solder feeding device for feeding molten solder to a substrate conveyed in a prescribed conveying direction by ejecting the molten solder from multiple ejecting ports toward the substrate, wherein, in at least one part of the area including the above multiple ejecting ports, the ejecting ports are provided in more than one rows relative to the substrate-conveying direction, including an upstream row and a downstream row and arranged in lines substantially along multiple inclined lines which are inclined to the substrate-conveying direction, and being arranged at a prescribed pitch in the direction perpendicular to the substrate-conveying direction, said ejecting ports further being arranged in such a manner that overlap dimensions relative to the direction perpendicular to the substrate-conveying direction of an ejecting port in the most upstream row and an ejecting port in the most downstream row of adjacent groups of ejecting ports are smaller than overlap dimensions relative to the direction perpendicular to the substrate-conveying direction of the adjacent ejecting ports of one group of ejecting ports arranged along the same inclined line.
The invention in another embodiment is a jet solder feeding device for feeding molten solder to a substrate conveyed in a prescribed conveying direction by ejecting molten solder from multiple ejecting ports toward the substrate, wherein, in at least one part of the area including the above multiple ejecting ports, the ejecting ports are provided in more than one rows relative to the substrate-conveying direction, including an upstream row and a downstream row and arranged in lines substantially along multiple inclined lines which are inclined to the substrate-conveying direction, and being arranged at a prescribed pitch in the direction perpendicular to the substrate-conveying direction, said ejecting ports further being arranged in such a manner that an ejecting port in the most upstream row and an ejecting port in the most downstream row of adjacent groups of ejecting ports do not overlap each other relative to the direction perpendicular to the substrate-conveying direction.
According to these configuration, the spacing between the adjacent groups of ejecting ports is larger than the spacing between the adjacent ejecting ports of one group of ejecting ports, and the balance of the flowing force of molten solder from each ejecting port is lost between the midpoint of the adjacent groups of ejecting ports and the midpoint of the adjacent ejecting ports of a group of ejecting ports. As a result, molten solder flows from the point where its flowing force is larger to the point where its flowing force is smaller. Accordingly, the flow of molten solder passing through midway between the adjacent groups of ejecting ports is created positively; therefore when the substrate is conveyed to the position where it is fed with molten solder, even if gas of vaporized flux is generated or air is admixed, the gas generated or the air admixed under the bottom surface of the substrate is satisfactorily discharged along the above described flow to the outside. This means no occurrence of poor wetting.
The invention in another embodiment is a jet solder feeding device including a first jet nozzle for feeding molten solder to the substrate and a second jet nozzle for removing excess solder from the substrate having been fed with solder, in this jet solder feeding device the ejecting ports are provided on the first jet nozzle.
According to this configuration, molten solder can be satisfactorily fed from the multiple ejecting ports provided on a first jet nozzle to a substrate.
The invention in another embodiment is a jet solder feeding device in which the portion provided with more than one rows of ejecting ports is arranged horizontally to the substrate-conveying direction.
The invention in another embodiment is a jet solder feeding device in which the portion provided with more than one rows of ejecting ports is inclined relative to the substrate-conveying direction in an upgrade manner toward the downstream side of the above direction.
According to this configuration, since molten solder ejected from the ejecting ports flows down toward the upstream side of the incline by self-weight, the relative speed between a substrate and molten solder is enhanced. This promotes wetting of the substrate and molten solder, in addition, even if gas of vaporized flux is generated or air is admixed, the gas generated or the air admized under the bottom surface of the substrate is satisfactorily discharged to the upstream side of the substrate-conveying direction.
The invention in another embodiment is a jet solder feeding device in which a substrate is conveyed in a prescribed upgrade substrate-conveying direction, the portion provided with more than one rows of ejecting ports is inclined relative to the substrate-conveying direction in an upgrade manner toward the downstream side of the above direction, and each ejecting port has a smaller bore diameter according as it is located nearer to the downstream side of the substrate-conveying direction.
According to this configuration, since the bore diameter of each ejecting port is set in such a manner that the ejecting ports located nearer to the downstream side of the substrate-conveying direction have a smaller bore diameter, the flow width of the molten solder ejected from the ejecting ports located in a row nearer to the downstream side of the substrate-conveying direction becomes smaller. Accordingly, when the molten solder ejected from ejecting ports located nearer to the downstream side of the substrate-conveying direction flows down along a corrugated plate, leveling of piles of the molten solder ejected from the ejecting ports located nearer to the upstream side of the substrate-conveying direction can be held to a minimum. In addition, since the ejecting ports located nearer to the upstream side of the substrate-conveying direction have a larger diameter, the piles of the molten solder ejected from such ejecting ports can be kept at a required height around each of their center portion.
The invention in another embodiment is a jet solder feeding device in which the jet solder feeding device comprises a corrugated plate, multiple ejecting ports being formed thereon, each of the ejecting ports on the corrugated plate being surrounded by a wall portion projecting upward.
According to this configuration, molten solder ejected from each eject port can be kept at a desired height stably.
The invention in another embodiment is a method for soldering a substrate conveyed in a prescribed conveying direction by ejecting molten solder from multiple ejecting ports toward the substrate to feed the molten solder thereto, in which, in at least one part of the area including the above multiple ejecting ports, the ejecting ports are provided in more than one rows relative to the substrate-conveying direction, including an upstream row and a downstream row and arranged at a second prescribed pitch in lines substantially along multiple inclined lines which are inclined to the substrate-conveying direction, and being arranged at a first prescribed pitch relative to the direction perpendicular to the substrate-conveying direction, the above first prescribed pitch being set to be larger than the above second prescribed pitch, whereby soldering is carried out for the portion to be connected arranged on the substrate with the molten solder ejected from the above multiple ejecting ports.
According this method, since the first prescribed pitch is larger than the second prescribed pitch, the balance of the flowing force of molten solder from each ejecting port is lost between the midpoint of the adjacent ejecting ports arranged at the first prescribed pitch and the midpoint of the adjacent ejecting ports arranged at the second prescribed pitch. As a result, molten solder flows from the point where its flowing force is larger to the point where its flowing force is smaller. Accordingly, the flow of molten solder passing through midway between the adjacent groups of ejecting ports is created positively; therefore when the substrate is conveyed to the position where it is fed with molten solder, even if gas of vaporized flux is generated or air is admixed, the gas generated or the air admixed under the bottom surface of the substrate is satisfactorily discharged along the above described flow to the outside. This means no occurrence of poor wetting.
The invention in another embodiment is a method for soldering a substrate conveyed in a prescribed conveying direction by ejecting molten solder from multiple ejecting ports toward the substrate to feed the molten solder thereto, in which, in at least one part of the area including the above multiple ejecting ports, the ejecting ports are provided in more than one rows relative to the substrate-conveying direction, including an upstream row and a downstream row and arranged in lines substantially along multiple inclined lines which are inclined to the substrate-conveying direction, and being arranged at a prescribed pitch relative to the direction perpendicular to the substrate-conveying direction, said ejecting ports further being arranged in such a manner that overlap dimensions relative to the direction perpendicular to the substrate-conveying direction of an ejecting port in the most upstream row and an ejecting port in the most downstream row of adjacent groups of ejecting ports are smaller than overlap dimensions relative to the direction perpendicular to the substrate-conveying direction of adjacent ejecting ports of a group of ejecting ports arranged along the same inclined line, whereby soldering is carried out for the portion to be connected arranged on the substrate with the molten solder ejected from the above multiple ejecting ports.
The invention in another embodiment is a method for soldering a substrate conveyed in a prescribed conveying direction by ejecting molten solder from multiple ejecting ports toward the substrate to feed the molten solder thereto, in which, in at least one part of the area including the above multiple ejecting ports, the ejecting ports are provided in more than one rows relative to the substrate-conveying direction, including an upstream row and a downstream row and arranged in lines substantially along multiple inclined lines which are inclined to the substrate-conveying direction, and being arranged at a prescribed pitch relative to the direction perpendicular to the substrate-conveying direction, said ejecting ports further being arranged in such a manner that an ejecting port in the most upstream row and an ejecting port in the most downstream row of the adjacent groups of ejecting ports do not overlap each other relative to the direction perpendicular to the substrate-conveying direction, whereby soldering is carried out for the portion to be connected arranged on the substrate with the molten solder ejected from the above multiple ejecting ports.
According to these methods of claims 10 and 11, the spacing between the adjacent groups of ejecting ports is larger than the spacing between the adjacent ejecting ports of a group of ejecting ports, and the balance of the flowing force of molten solder from each ejecting port is lost between the midpoint of the adjacent groups of ejecting ports and the midpoint of the adjacent ejecting ports of a group of ejecting ports. As a result, molten solder flows from the point where its flowing force is larger to the point where its flowing force is smaller. Accordingly, the flow of molten solder passing through midway between the adjacent groups of ejecting ports is created positively; therefore when the substrate is conveyed to the position where it is fed with molten solder, even if gas of vaporized flux is generated or air is admixed, the gas generated or the air admixed under the bottom surface of the substrate is satisfactorily discharged along the above described flow to the outside. This means no occurrence of poor wetting.
FIG. 1 is a top view partly broken away to show the main part of a jet solder feeding device according to a first embodiment of the present invention;
FIGS. 2a and 2b are views in top and in front elevation in section, respectively, partly broken away to show the main part of a jet solder feeding device according to a second embodiment of the present invention;
FIG. 3 is an enlarged top view partly broken away to show the flow conditions of molten solder in the jet solder feeding device of FIG. 2, the visible outline of the portion having been subjected to coining being omitted to clarify the amount of overlapping;
FIGS. 4a and 4b are views in top and in front elevation in section, respectively, partly broken away to show the main part of a jet solder feeding device according to a third embodiment of the present invention;
FIG. 5 is an enlarged top view partly broken away to show the flow conditions of molten solder in the jet solder feeding device of FIG. 4;
FIG. 6 is a schematic view in perspective of a jet solder feeding device;
FIG. 7 is a schematic elevational view in section of a jet solder feeding device;
FIGS. 8a and 8b are views in top and in front elevation in section, respectively, partly broken away to show the main part of a jet solder feeding device according to a prior art; and
FIG. 9 is an enlarged top view partly broken away to show the flow conditions of molten solder in the jet solder feeding device of FIG. 8.